Abstract

For the combustion of natural gas in high temperature glass furnaces a computational model “Furnace” has been developed. It includes 3-D turbulent flow, flame chemistry, radiative heat transfer and the formation of soot and of the pollutant NO. Turbulent fluctuations have been taken into account, and are shown to have a large effect on thermal radiation and NO-formation. Spectral behaviour of gas radiation results in changes of heat transfer efficiency up to 5%, depending on refractory emissivity.

The model has been employed to predict NO formation for different burner geometries. In general, a decrease in mixing of gas and air results in a reduction of 1600 to 400 ppm in flue gas NO concentration. Except for some of the low mixing flames, however, they lead to a lower burnout and a very high CO level in the flue gas. A comparison with semi-technical furnace tests shows that the model can predict NO formation reasonably well. With this computational model the designer of furnaces and burners can study further possibilities for increased furnace performance and low NO emissions.